DupesPlus

Turn duplication exploits on or off from an in-game GUI. Paper 1.21.11.

Vanilla Minecraft has a handful of well-known "dupes" (TNT, sand, rails, carpet, end-portal gravity blocks). Paper's default behaviour is a single global switch that either allows all of them or none of them. DupesPlus gives you fine-grained per-type control, all from one chest GUI, with changes saved instantly.

Perfect for SMPs where you want TNT dupes for cannons but no infinite sand farms, or dupe-friendly minigame servers that want an admin panel instead of digging through YAML.

Features

Toggle TNT, Sand, Rails, Carpet, and End Portal dupes independently
Clean 27-slot chest GUI opened with /dupes
Per-dupe settings sub-menu: max blocks per piston action, per-position cooldown
Rail sub-toggles for powered / detector / activator rails
Auto-configures Paper's paper-global.yml for you (comment-preserving; tells you when to restart)
Chat commands with full tab-completion
Ops get an optional broadcast whenever a dupe is toggled
Zero-allocation fast path — no performance cost when everything is enabled

Installing

Drop DupesPlus-1.1.0.jar into your server's plugins/ folder
Restart the server
On first boot, DupesPlus enables allow-piston-duplication in paper-global.yml. If it changed it, restart one more time so Paper picks it up (the console log tells you)
In-game: /dupes opens the manager

Commands

Command	Permission	What it does
`/dupes`	`dupesplus.use`	Opens the manager GUI
`/dupe help`	`dupesplus.admin`	Shows the command list in chat
`/dupe status`	`dupesplus.admin`	Shows the current state of every dupe
`/dupe toggle <tnt\|sand\|rails\|carpet>`	`dupesplus.admin`	Toggles a piston dupe on/off (live)
`/dupe toggle endportal`	`dupesplus.admin`	Toggles the end-portal dupe (restart required)
`/dupe set <type> <setting> <value>`	`dupesplus.admin`	Sets a specific value directly
`/dupe reload`	`dupesplus.admin`	Reloads `config.yml` from disk

Settings for /dupe set: enabled, max-per-cycle, cooldown-ticks, plus include-powered-rails / include-detector-rails / include-activator-rails for rails.

Examples:

/dupe toggle tnt # flip TNT on or off

/dupe set sand max-per-cycle 4 # only allow up to 4 sand per piston push

/dupe set rails cooldown-ticks 20 # 1-second cooldown between rail dupes at the same spot

/dupe set rails include-powered-rails false

Using the GUI

/dupes opens a chest with:

TNT / Sand / Rail / White Carpet icons — each shows status, max per cycle, and cooldown
- Left-click → toggle on/off
- Shift-right-click → open its settings sub-menu
End Portal Frame (top row) — toggles the end-portal gravity-block dupe (needs a restart)
Barrier — close the menu
Book — runs /dupe help

Settings sub-menu:

Anvil — max per cycle: left-click +1, right-click −1, shift adds ±10
Clock — cooldown ticks: same interaction
Lever — enabled on/off
Arrow — back to the main menu

All changes save to config.yml immediately.

Permissions

Permission	Default	Grants
`dupesplus.use`	op	`/dupes` and the GUI
`dupesplus.admin`	op	all `/dupe` subcommands

Compatibility

Paper 1.21.11 — primary target, tested end-to-end
Paper 1.21.0 – 1.21.11 — best-effort (uses only Paper API, no NMS)
Java 21 required
Not for Spigot/Bukkit (relies on Paper-only mechanics) — not for Folia

Heads-up

DupesPlus rides Paper's allow-piston-duplication and allow-unsafe-end-portal-teleportation, which Paper classifies as unsupported settings. That means Paper can change or remove them in a future update — if they do, no plugin can bring the dupes back. This is a convenience layer for controlling exploits Paper already exposes; it doesn't create them.

Source & License

MIT-licensed. Open source. No telemetry, no external calls, no dependencies beyond the Paper API.

Suggested CurseForge fields:

Summary (short blurb): Toggle TNT, sand, rail, carpet, and end-portal dupes from an in-game GUI. Per-type control on top of Paper's single global switch.
Category: Bukkit Plugins
Tags: Server Utility · Fun · Admin Tools
Game version: 1.21.11 (also list 1.21 – 1.21.11 as "supported")

Dupes Returned